The case for recycling concrete to curb emissions

Concrete is among the most widely used construction materials and can be found in almost all modern structures, be they houses, flyovers, dams or bridges. The Roman Pantheon and, possibly, even the Pyramids of Egypt were built using a form of concrete.

Many of the marvels of civil engineering would not have been built had it not been for concrete, but these structures have come at a great cost to Mother Earth.

Every tonne of cement that goes into making concrete releases approx. 800 to 900 kg of CO2 emissions into the atmosphere. Buildings & Construction together are responsible for 39% of global carbon emissions. The enormity of the problem is clearly visible. Since construction sector is vulnerable to raw material supply problems and price volatility, it does make sense to focus on resource efficiency, and the reuse of materials. It is now established that adopting improved construction process could reduce the adverse impacts on the environment and reusing construction & demolition (C&D) waste is a viable alternative.

Future with LCC

Companies across the world are investing to curb the impact of carbon emissions on climate. In India, Godrej & Boyce (G&B) has been investing in technologies, processes and alternative materials to address this growing concern. Since global warming affects all of us, G&B’s efforts at developing low carbon concrete low carbon concrete (LCC) is a small step towards meeting sustainability goals. LCC reduces the amount of cement used. This automatically brings down CO2 emissions.

Godrej & Boyce’s strategic business unit Godrej Construction has variants of LCC products such as Enviro TUFF, Thermo TUFF and Xtra Tuff in the market.

Autoclaved aerated concrete (AAC), an environment-friendly replacement for bricks, is gaining prominence in India. They are stronger, lighter, offer better insulation, are eco-friendly and sustainable, are thermally insulated and energy resistant and facilitate faster construction. A government-mandated use of these bricks for public infrastructure projects can be a good initiative.

In line with the Godrej & Boyce values towards ‘Environment Stewardship’, Godrej Construction, has joined Build Ahead Coalition with Xynteo to accelerate decarbonization efforts for construction sector in India and encourage collaboration for collectively tackling the challenge of achieving a net-zero built environment in India.

Concrete as a CO2 sink

Concrete has another under-appreciated quality: It can absorb free carbon dioxide, but the rate of absorption is very slow. Can we then use concrete as a CO2 sink? Many carbon infusion technologies are being developed to absorb atmospheric carbon dioxide. They are still at the pilot stage. This technology has seen success in few pilot projects in countries like the US, Canada and Singapore. Experts estimate it will take another 4-5 years before it can become mainstream.

Meanwhile, we can adopt the practice of recycling concrete to reduce carbon emissions. This involves pulverising concrete debris from construction and demolition (C&D) waste to make recycled concrete aggregates, which can be suitably used as a substitute for natural aggregates. The entire process involves lower CO2 emissions over the product lifecycle across the value chain from raw materials procurement to the delivery of finished products. Scandinavian countries are the pioneers of this technology. In India, Godrej & Boyce has set up a state-of-art manufacturing plant for Recycled Concrete Materials in the Mumbai suburb of Vikhroli, which has a capacity of recycling 300 tonnes of concrete debris per day.

C&D waste recycle, the need of the hour

Ministry of Road Transport & Highways (MoRTH) has taken steps to finalize guidelines for value engineering during preparation of feasibility reports of proposed highway projects for promoting use of C&D waste.

To promote higher uptake of recycled products made using C&D waste in the construction sector, there needs to be more emphasis on development of public procurement policy, lowering GST slab rates for recycled products, incorporating new guidelines in relevant building design codes and standards to encourage use of C&D waste right at the design stage of any project. Incentivizing all stakeholders involved in C&D waste management would provide financial benefits for better implementation of C&D waste rules and framework. C&D waste recycling plants must necessarily be a regional play rather than a national play. Wider acceptance of this technology needs a mindset change.

It will take time and effort to change perceptions before this can happen. That is because many end-users believe recycled concrete products are inferior. In fact, recycled concrete products are at par with the virgin product and meets all performance parameters and compliance standards.

A government-mandate towards reducing CO2 emissions in the construction sector can be a good first step that will set the ball rolling towards achieving a more circular economy.

Reference:

The World Green Building Council’s Global Status Report 2017.